This disclosure relates to snow retention devices attached to roofs. Specifically, this disclosure relates to snow guards.
Snow guards are snow retention devices designed to prevent snow and ice from avalanching off roofs. Snow guards are different from roof edge deicing systems. Roof edge deicing systems use heated pads, heated membranes, or heated cables, mounted flush or below the roof shingles, tiles, or other metal roof surface, at the roof edge. Their purpose is to prevent heavy ice, or ice dams, caused by snow melting and re-freezing at the warmer roof edge from accumulating at either the roof edge or gutter. In contrast, snow guards are snow retention devices mounted above the roof surface, typically away from the roof edge. Their purpose is to create a barrier, or create friction, to prevent snow from avalanching off a pitched (i.e., an angled) roof.
There are several types of snow guards. These include pad-style, pipe-style, and bar-style snow guards. Historically, these derive from two concepts for snow retention developed several hundred years ago. The first concept was to place stationary rocks on roofs to provide friction and prevent snow from sliding down the roof slope. The second concept was to position logs on the roof parallel to, but away from, the roof edge to act as a fence or barrier for snow and ice. Pad-style snow guards are analogous to placing stationary rocks on the roof surface. Pipe-style and bar-style snow guards are analogous to placing logs parallel to, but away from, the roof edge.
Pad-style snow guards, typically comprise individual projections, cleats, or pads that project above the roof surface. Their purpose is to provide friction and prevent snow and ice from sliding down a sloped roof.
Pipe-style snow guards use one or more enclosed pipes or tubes positioned above the roof surface to create a barricade for snow to accumulate. The pipes or tubes are often positioned above the roof surface by brackets, seam clamps, or mounting devices depending on the type of roof. The pipes or tubes are typically positioned parallel to the length-wise edge of the roof. More than one pipe or tube can be positioned above one another to act like a fence or barrier for snow. The pipes or tubes are typically placed well away from the roof edge so if snow accumulates and spills over the top of the snow guard, it is less likely to avalanche over the edge of the roof.
Bar-style are like pipe-style snow guards except vertical bars or open L-brackets are used in place of enclosed pipes or tubes. Both bar-style and pipe-style snow guards are often collectively called snow guard rail systems.